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Biomedical subjects

I S Kulaev

Publications and source records attributed to I S Kulaev.

221 records · Page 13Linked to original sources

[Lytic action of lysoamidase from Xanthomonas sp. correlates with the presence of the target ribitol teichoic acids in the cell wall of gram-positive bacteria].

Lysoamidase, a bacteriolytic complex from the culture liquid of Xanthomonas sp., hydrolyzed the cells walls of Staphylococcus aureus, Streptomyces chrysomallus, and Streptomyces azureus, which contain ribitol teichoic acids in addition to peptidoglycan. The cell walls of Streptomyces roseoflavus, Glycomyces harhinensis, and Nocardiopsis dassonvillei, containing glycerol teichoic acids, were not hydrolyzed by lysoamidase. The extent of the hydrolysis of 20-h Str. chrysomallus cells and cell walls, containing 40% ribitol teichoic acids, was considerably higher than that of 40-h cells and cell walls, containing 15% teichoic acids. Homogeneous bacteriolytic enzymes of the lysoamidase complex (muramidase and two bacteriolytic peptidases) most efficiently hydrolyzed S. aureus and Str. chrysomallus cell walls, characterized by the highest content of ribitol teichoic acids, and did not hydrolyze purified peptidoglycan.

Anti-Bacterial Agents↗

[Effect of cell wall polyphosphates on the sensitivity of the yeast Saccharomyces carlsbergensis to the damaging action of cetyltrimethylammonium bromide].

The effect of cetyltrimethylammonium bromide (CTAB) on Saccharomyces carlsbergensis cells grown in orthophosphate-containing medium and on cells starved of phosphorus was studied by electroorientation spectroscopy. CTAB (20 microM) was found to substantially damage the plasma membrane (PM)) of cells grown in the presence of orthophosphate, while cells starved of phosphorus were damaged to a lesser extent. Biochemical analysis of the content of inorganic polyphosphate (poly(P(i))) in the cells, as study of their capacity to adsorb 9-aminoacridine, a fluorescent cationic dye, suggested that the different sensitivity of the plasma membrane to CTAB was due to differences in the content of polyanionic molecules of poly(P(i)) in the cell wall and consequent differences in its net negative charge. Magnesium cations increased the time of CTAB penetration through the cell wall and reduced the damage inflicted on the PM.

Anti-Infective Agents, Local↗

[Change in inorganic polyphosphate chain length depending on the stage of Saccharomyces cerevisiae growth].

The dynamics of the content and the degree of polymerization of polyphosphates (PPs) during the growth of Saccharomyces cerevisiae VKM Y-1176 was studied by chemical methods and P NMR spectroscopy. The overall PP content of Saccharomyces cerevisiae cells growing in orthophosphate-sufficient medium was found to increase until glucose was exhausted in the medium. In the early logarithimic phase, the degree of polymerization of PPs (high-polymeric PPs in particular) fell drastically. Further cultivation of yeast in the glucose-depleted medium led to a decrease in the cellular content of all PP fractions without any considerable shortening of their chain length; by the 24th h, high-polymeric PPs accumulated in the cells. Shortening of PPs against a background of their intense synthesis in yeast cells growing in glucose-and orthophosphate-sufficient medium can be explained by the involvement of so far unknown mechanisms of activation of polyphosphate-depolymerizing enzymes.

Culture Media↗

[Hypochromic effect of signal attenuation in 31P-NMR spectra of linear polyphosphates].

Chemical shifts in 31P-NMR spectra of linear polyphosphates were studied. In each polyphosphate species tested, the sum of signal intensities of the internal (core) phosphate groups was proportional to the concentration of each polyphosphate, but the contribution of such groups to the total intensity of the signal decreased with increasing the length of the polyphosphate chain. An equation for estimating the polyphosphate chain length in biological objects taking into account a decrease in the 31P-NMR spectral intensity is proposed.

Nuclear Magnetic Resonance, Biomolecular↗